1. Field of the Invention
The present invention relates to an image forming apparatus such as a copying machine including a control system which is very simple in construction yet capable of controlling various processes with a higher degree of accuracy in a very reliable manner.
2. Description of the Prior Art
In the prior copying machines, only the combinations of relay circuits or the so-called hard wire logic circuits have been used for controlling the sequences and timings of processing means which is used in this specification to refer to all of the means required for reproducing a copy from an original such as charging, exposure, developing, and transferring means. Since the relay circuits and the logic circuits are combined in order to attain a specific purpose, the recombination of these circuits for other purposes requires much labor and time. Furthermore the circuit constructions and wiring arrangements for controlling a large number of processing means are very complex so that poor reliability results and inspection and maintenance are difficult.
It has been proposed to control the sequence of operations of the processing means by a use of a program, but the conventional copying machine control systems incorporating the sequence control programs are still very complex in circuit construction.